Jan Fritz MD, Presenter: Nothing to Disclose

Sudhir Kathuria, Abstract Co-Author: Nothing to Disclose

Aaron Flammang, Abstract Co-Author: Employee, Siemens AG

John A. Carrino MD, MPH, Abstract Co-Author: Research Grant, Siemens AG Research Grant, Carestream Health, Inc Research Consultant, General Electric Company

Avneesh Chhabra MD, Abstract Co-Author: Research Grant, Siemens AG Research Consultant, Siemens AG Research Grant, Integra LifeSciences Holdings Corporation Research Grant, General Electric Company

Posterior femoral cutaneous nerve (PFCN) neuropathy is a cause chronic pelvic pain syndrome and a major differential diagnosis of pudendal neuralgia. Selective diagnostic nerve block are especially challenging because of small nerve size and lack of visibility of the nerve on ultrasound or CT. In contrast, high-field MR neurography displays the course of the PFCN, which can then be used for accurate targeting and selective drug delivery. Therefore, the purpose of this study was to assess the technical accuracy, effectiveness, and safety of MR neurography-guided posterior femoral cutaneous nerve blocks.

A retrospective analysis of 12 posterior femoral cutaneous nerve blocks in 8 subjects (6 (75%) female, 2 (25%) male; mean age, 47 years; range, 42 – 84 years) with chronic perineal pain suggesting PFCN neuropathy was performed. Procedures were performed at a clinical wide-bore 1.5 Tesla MR imaging system with limited pre-procedural MR neurography. Commercially available, MR-compatible 20 G needles were used. Entities assessed were technical success, defined as injectant surround the targeted posterior femoral cutaneous nerve on post-intervention MR images; effectiveness, defined as post-interventional regional anesthesia of the target area innervation downstream from the posterior femoral cutaneous nerve block; rate of complications; and length of procedure time.

MR neurography-guided injections were technically successful in 12/12 cases (100%) with uniform perineural distribution of the injectant. All blocks were effective and resulted in post-interventional regional anesthesia of the expected areas (12/12, 100%). No complications occurred during the procedure or during follow-up. The average total procedure time was 45 min (30-70) min.

Our initial results suggest that selective MR neurography-guided PFCN blocks are technically accurate, effective and safe. Larger studies are needed to confirm our initial findings.

MR neurography guidance is a promising new technique for selective blocks of the PFCN, which is imporant in the diagnostic work-up and management of patients with chronic pelvic pain syndrome.

Fritz, J, Kathuria, S, Flammang, A, Carrino, J, Chhabra, A, Selective MR Neurography-guided Posterior Femoral Cutaneous Nerve Blocks.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12026958.html